1. Field of the Invention
The present invention relates in general to spring mattresses for beds and, more particularly, to a structural improvement in such spring mattresses for providing a hard spring mattress effect as well as a typical soft spring mattress effect for a mattress by providing a hard spring for one side of the mattress and a typical soft spring for the other side of the mattress and integrating the hard and soft springs into a double structure spring of the mattress.
2. Description of the Prior Art
Conventionally, commercialized spring mattresses for beds are soft spring mattresses using soft springs, meeting taste of healthy young peoples. However, some peoples, particularly trouble-waisted peoples, old peoples and fatty peoples, are preferred to use hard spring mattresses rather than use the soft spring mattresses, nevertheless they have inevitably endured inconvenience caused by use of the soft spring mattresses because there is no commercialized hard spring mattress. In this regard, it needs to provide hard spring mattresses for such peoples. Furthermore, it will be more profitable to provide a spring mattress having the hard spring mattress effect as well as the soft spring mattress effect because such a spring mattress will commonly meet taste of peoples preferred to use the hard spring mattress and taste of peoples preferred to use the soft spring mattress.